Computer system having drive temperature self-adjustment for temperature-sensitive measurements

ABSTRACT

A computer system that adjusts an internal temperature of a hard disk drive (HDD) during HDD testing. An HDD test program under the control of the computer system is performed within a pre-determined optimal test temperature range. The HDD is kept within this pre-determined test temperature range by the computer system switching HDD operation modes back and forth between a higher heat generating Rapid Seek Mode and a lower heat generating IDLE mode. The HDD is thus kept within the optimal test temperature range without the use of external heating and/or cooling devices.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates in general to storage systems, and inparticular disk drives. Still more particularly, the present inventionrelates to a computer system capable of controlling the temperature of adisk drive during testing using the disk drive's own hardware andsensors.

2. Description of the Related Art

A hard disk drive (HDD) is a digital data storage device that writes andreads data via magnetization changes of a magnetic storage disk alongconcentric tracks. The HDD is tested before being shipped to thecustomer. In addition, the customer often tests the HDD on a periodicbasis after the HDD is operational. The HDD can be tested either foron/off failures or for gradual performance degradation.

On/off failures are failures in which an item fails, such as a cablebreaks, a disk does not spin, a read/write head does not function atall, etc. Such failures are easy to identify and locate, but may requireputting the HDD in an artificial condition, such as temperatureextremes, high vibration, etc., that makes such an on/off failure morelikely. Such conditions can cause undetected damage to the HDD, and thuson/off failure analysis has inherent limitation.

Gradual performance degradation occurs before an on/off failure. Whilesuch performance degradation may be caused by the same conditions thatcause an on/off failure, evaluation of gradual performance degradationis typically performed under conditions much less severe than those thatmay cause an on/off failure.

Data produced by gradual performance degradation is used to conduct apredictive failure analysis. The gradual performance degradation datacan be extrapolated or otherwise manipulated/evaluated to predict anultimate on/off failure, or else an unacceptable performancedegradation. This type of data extrapolation is referred to asPredictive Failure Analysis (PFA). PFA evaluates performance usingeither a “symptom driven” process or a “measurement driven” process.

The symptom driven process evaluates error logs. That is, when a failurein disk rotation speed, data read/writes, noise reduction, etc. occurs,an error log is generated, allowing the tester to identify the cause ofthe problem. Such a process is similar to an on/off failure analysis,except that the HDD has not entirely failed; rather only a partialfunction of the HDD has failed.

The measurement driven process detects Generalized Error Measurements(GEM), which detects changes in performance, although not necessarilyfunctional errors. That is, a GEM may detect an increase in the distancebetween a read/write head and a disk surface, or an increase in noise ina digital signal read by the read/write head, but such increases do notcause a failure of the entire HDD or an HDD component, and thus are notconsidered “errors.” Nonetheless, such GEMs are good indicators ofpotential problems, especially if the conditions causing the GEMs areallowed to persist or increase. For example, if the distance between theread/write head and disk surface (known as the “flying height” of thehead) increases beyond an expected tolerance as the operatingtemperature of the disk surface increases, then a failure can bepredicted if the temperature continues to rise beyond the normaloperating temperature or remains at the normal operating temperature foran extended period of time.

Test condition parameters, including temperature, required during thedetection of GEMs are established by a test engineer. For example, thetest engineer may write a test program that measures flying height whenthe disk drive is operating at 30° C.±4°. In order to keep the HDD at ornear this range of temperatures, various methods are used in the priorart. Most such methods include test bench heating or cooling devices,which force regulated hot or cold air across or into the HDD until thedesired test temperature condition is reached. Such heaters/coolersrequire additional test bench footprint space, electrical outlets,feedback controls, and cost.

In addition, an operations computer may test its HDD periodically. Suchtesting also requires the temperature of the HDD to be withinpre-determined levels during testing, typically using the HDD's on-boardcooling system (fan). However, such fans can only cool, not warm up, theHDD.

What is needed, therefore, is a method for regulating the temperature ofan HDD, which is being tested, without the need for and use ofadditional hardware.

SUMMARY OF THE INVENTION

In view of the foregoing, the present invention provides a computersystem that adjusts an internal temperature of a hard disk drive (HDD)during HDD testing. An HDD test program under the control of thecomputer system is performed within a pre-determined optimal testtemperature range. The HDD is kept within this pre-determined testtemperature range by the computer system switching HDD operation modesback and forth between a higher heat generating Rapid Seek Mode and alower heat generating IDLE mode. The HDD is thus kept within the optimaltest temperature range without the use of external heating and/orcooling devices.

The above, as well as additional objectives, features, and advantages ofthe present invention will become apparent in the following detailedwritten description.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are setforth in the appended claims. The invention itself, however, as well asa preferred mode of use, further purposes and advantages thereof, willbest be understood by reference to the following detailed description ofan illustrative embodiment when read in conjunction with theaccompanying drawings, where:

FIG. 1 a depicts a preferred hard disk drive (HDD) and HDD tester usedin the present invention;

FIG. 1 b illustrates additional detail of a disk platter stack used inthe HDD of FIG. 1 a;

FIG. 2 is a chart of temperatures generated by different operationsmodes, Rapid Seek and IDLE, of the HDD;

FIG. 3 is a chart showing the non-linear relationship betweenPerformance Measurement Units (PMUs), which quantify HDD operationanomalies, and time when the HDD is in an IDLE mode of operation;

FIG. 4 is a chart showing the linear relationship between PMUs and thetemperature of the HDD;

FIG. 5 is a flow chart of steps taken to rapidly increase the initialinternal temperature of the HDD for testing by activating the Rapid SeekMode of the HDD;

FIG. 6 is a flow chart of steps taken using the Rapid Seek and IDLEmodes to maintain the internal temperature of the HDD during testing;and

FIG. 7 is a flow chart of steps taken using the Rapid Seek and IDLEmodes to ensure that the HDD is within a requisite temperature rangeneeded to conduct a HDD test.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

With reference now to the figures and in particular FIG. 1 a, there isdepicted a block diagram of a hard disk drive (HDD) 100 as contemplatedby the present invention. HDD 100 has a set of hard disks 120, which arerigid platters composed of a substrate and a magnetic medium. Since thesubstrate is non-magnetic, both sides of each hard disk 120 can becoated with the magnetic medium so that data can be stored on both sidesof each hard disk 120.

An actuator arm 124 moves a slider 132, which is gimbal mounted to theactuator arm 124. The slider 132 carries a magnetic read/write head 122to a specified lateral position above the surface of the hard disk 120when a voice coil motor (VCM) 126 swings the actuator arm 124.

With reference now to FIG. 1 b, there is depicted additional detail ofhard disks 120. Hard disks 120 are a stack of hard disk platters, shownin exemplary form as hard disks 120 a-b. Preferably, more than twoplatters are used, but only two are shown for purposes of explanation.As a spindle motor 132 turns spindle 128, each hard disk 120 connectedto spindle 128 rotates at speeds in excess of 10,000 revolutions perminutes (RPMs). Each hard disk 120 has two surfaces, one or both ofwhich can be magnetized to store data. Thus, hard disk 120 a is able tostore data on both sides using read/write heads 122 a and 122 b. Harddisk 120 b stores data on only one side using read/write head 122 c.Thus, the system illustrated in FIG. 1 b is a two-platter three-headHDD. By swinging the actuator arm 124 (and thus causing the movement ofslider 132 and read/write head 122) and rotating the spindle 128 (andthus spinning hard disk 120), read/write head 122 can be positionedabove any spot above the surface of the hard disk 120.

Referring again to FIG. 1 a, data reads/writes between a host system 102and magnetic head 122 are under the control of a controller 104.Controller 104 includes an interface (I/F) 112 coupled to host system102. Coupled to I/F 112 is a hard disk controller (HDC) 108, whichcoordinates read/write operations, and controls modes of operation ofHDD 100, including Active Seek and IDLE Modes, about which more isdiscussed below.

Coupled to HDC 108 is a random access memory 106, which caches data tobe read/written at hard disk 120. Read/write circuit 116 includes ananalog-to-digital converter (ADC) and a digital-to-analog converter(DAC). The ADC is used to convert analog signals into digital signalsfor reads from the hard disk 120. The DAC is used to convert digitalvalues into appropriate analog signals for writes to the hard disk 120.A microprocessor unit (MPU) 110, under the control of a micro-programstored in read only memory (ROM) 114, controls a VCM driver 118. VCMdriver 118 controls movement of the VCM 126 using a 9-bit DAC, whichconverts a digital control signal from MPU 110 into an analog controlsignal for VCM 126. Typically, VCM driver 118 also works in coordinationwith a controller (not shown) for spindle 128, to provide properpositioning of read/write head 122 above the surface of hard disk 120during read/write operations.

Testing of HDD 100 is performed under the control of a HDD tester 136.HDD tester 136 may be under the control of a standalone test computer(not shown) in a test laboratory, a program that is embedded in ROM 114,or a test program in host system 102, which is running HDD 100 underpost-delivery operational conditions under the control of user orautomatic hardware. HDD tester 136 samples data from read/write circuit116, evaluating the form (amplitude, noise, etc.) as well as content(ones and zeros) of the data. HDD tester 136 also receives temperaturereadings from thermal probe 130, which measures the temperature insidethe housing for HDD 100. HDD tester 136 also receives test data from atest circuitry 134, which includes circuitry for measuring flight heightof read/write heads 122, deformation of slider 132, rotational speed ofspindle 128, seek travel time of read/write heads 122, etc. HDD tester136 is also able to control modes of operation of HDD 100, includingRapid Seek Mode and IDLE Mode, via communication with HDC 108.

As described above, HDD in an exemplary form has two seek modes: RapidSeek and IDLE. During Rapid Seek Mode, more than 150 data seeks/secondmay occur. This generates a large amount of heat, mainly from currentflowing through coils (not shown) in VCM 126, but also due to metalfriction caused by contacts against bearings (not shown) in VCM 126.During IDLE mode, the disks continue to spin at normal operationalRPM's, but VCM 126 is much less active, as there are perhaps as few as 5data seeks/minute. This slower seek mode results in much less currentflowing through VCM 126, resulting in much less heat dissipation fromthe coils in VCM 126.

It is noted here that while the present invention uses Rapid Seek Modeand IDLE mode to illustrate different seek modes having different seekrates and heat generation/dissipation, the present inventioncontemplates any two seek modes having different seek rates withcorrelative different heat generation/dissipation levels. Thus a firstseek mode is defined as any mode having a higher seek rate than a secondseek mode, such that the first seek mode generates/dissipates more heatthan the second seek mode. In a preferred embodiment, the first seekmode has a seek rate between 50 and 150 seeks/second, and the secondseek mode has a seek rate between 1 and 50 seeks/minute.

The different amounts of heat generated by the Rapid Seek and IDLE modesare charted in FIG. 2, which depicts temperature/time curves for theRapid Seek Mode and the IDLE mode. As shown, the Rapid Seek Mode notonly generates higher ultimate levels of heat after reaching steadystate (reaching about 52° C. after approximately 50 minutes), but RapidSeek Mode also generates heat faster. Thus, the Rapid Seek Mode causesthe drive temperature to reach 42° C. in only 20 minutes, compared tothe IDLE Mode that causes the drive temperature to reach 42° C. in about50 minutes.

Performance Measurement Units (PMUs) are quantified measurement unitsdescribing performance of a HDD. An exemplary PMU is IBM's GeneralizedError Measurement (GEM) described above. PMUs describe performancedeviations. A PMU does not represent a true error, but rather adeviation from optimal performance. Thus, PMUs are quantified for issuessuch as high or low read/write head flying height, signal noise fromreadings from the read/write head, channel noise, signal coherence,irregular signal amplification, etc.

As described in the graph of FIG. 3, the number of PMUs increase duringthe time that the HDD is warming up. The longer the HDD is warming up,the more PMUs are generated, until the HDD reaches its steadytemperature state. Thus, the graph of FIG. 3 has a linear relationshipwith the IDLE chart-line of FIG. 2. This relationship is described in amore general manner in FIG. 4, which shows a linear correlation betweenthe number of PMUs and the HDD temperature. This linear correlation isthe same whether the HDD temperature is generated during Rapid Seek Modeor IDLE Mode.

The present invention takes advantage of the different heat generatingrates/levels of the Rapid Seek Mode and the IDLE Mode shown in FIG. 2.One method of utilizing this difference is shown in the flow-chart ofFIG. 5, which depicts an HDD being initially turned on for testing(block 500). The HDD needs to be heated, as soon as possible, to arequisite test temperature range. To accomplish this heating, the HDD isinitially run in Rapid Seek Mode (block 502), until the HDD actualtemperature (T_(i)) reaches the desired test temperature range (queryblock 504), as determined by an HDD tester using a temperature probewithin the HDD. This desired test temperature is defined/selected by atest program in the HDD tester. The desired test temperature range isdefined as temperature “T” plus or minus acceptable deviationtemperature “dT.”

When running the HDD in Rapid Seek Mode has generated enough heat toreach the desired test temperature range, the HDD is then placed in IDLEmode (block 506), since the HDD test program should be performed (or insome cases must be performed) while the HDD is in IDLE mode. The HDDtest program is then run (block 508). In a preferred embodiment, thetest program is run at a steady-state temperature for IDLE mode.Referring back to FIG. 2, while in the IDLE mode, once the HDD reachesabout 42° C., the HDD will continue to remain at this temperature aslong as the HDD remains in IDLE mode. However, by initially running theHDD in the Rapid Seek Mode, this steady state temperature is reachedmuch faster (in about 20 minutes instead of the 50 minutes it would havetaken the IDLE mode). Thus, the present invention allows the HDD towarm-up to the desired HDD test temperature in a significantly shorteramount of time, thus improving test throughput and resulting insignificant savings in time and money.

After reaching an optimal test temperature, it would be advantageous tomaintain such an optimal test temperature, assuming that remaining inIDLE mode alone will not keep the testing temperature steady. Referringthen to FIG. 6, an initial condition is assumed that the HDD test iscurrently running in the proper test temperature range (block 602). TheHDD temperature is then constantly monitored by the HDD tester using thethermal probe inside the HDD, and this internal temperature is adjustedusing the Rapid Seek Mode and IDLE Modes of the HDD. If the temperature(T_(i)) of the HDD is too high (query block 604), then the HDD testprogram is suspended (block 606) and the HDD allowed to continue in IDLEmode until it cools down enough to resume the HDD test. If thetemperature of the HDD is too low (query block 608), then the HDD testis suspended (block 610), and the HDD drive is run in Rapid Seek Modeuntil the HDD is warm enough to continue the HDD test. As soon as theHDD is back within the proper temperature range, then the HDD test isresumed (block 612) and continues until the HDD test is complete (queryblock 614).

Periodically, an operational HDD needs to be tested. FIG. 7 describessuch a situation and a preferred embodiment of the present invention.Assuming that an HDD is in normal operation in a computer system, adetermination is made (query block 702) as to whether it is time toconduct an HDD test. If so, then the HDD test program reads/determineswhat the requisite test temperature range is for the HDD test (block704). The HDD tester, using the temperature probe inside the HDD,compares the initial internal temperature (T_(i)) of the HDD with therequisite test temperature range (T±dT) for the HDD test program. If theinitial temperature is too high (query block 706), then the HDD is putinto IDLE mode (block 708) to cool down. If the initial temperature istoo low (query block 710), then the HDD is put into Rapid Seek Mode(block 712) to heat up. When the HDD is in the proper temperature range,the HDD is put into IDLE mode (if not already) and the HDD test is run(block 714). The temperature is continually monitored, and the HDD testis suspended whenever the HDD temperature is outside the testtemperature range (blocks 708 and 712). This monitoring/adjustmentcontinues until the HDD test is completed (query block 716).

The present invention therefore affords a method for reaching andmaintaining a desired internal temperature of a HDD during testingoperations using only existing hardware and existing HDD modes ofoperation. By using the Rapid Seek Mode, the HDD is quickly put incondition for testing. By maintaining the HDD within the proper range oftemperatures as described, false errors, caused by testing at animproper temperature, are avoided, and product yield is increased.

While the present invention has been described and illustrated usingseek modes having different heat generation/dissipation levels, it isunderstood that the scope of the present invention includes the use ofany two modes of HDD operation in which the HDD has two modes ofoperation, the first mode generating/dissipating more heat than thesecond mode of operation. Thus, more or less heat may be generated indifferent modes of operation that have different speeds of spindle motor132, different clock/operation speeds of MPU 110, etc.

It should be further understood that at least some aspects of thepresent invention may alternatively be implemented in a program product.Programs defining functions on the present invention can be delivered toa data storage system or a computer system via a variety ofsignal-bearing media, which include, without limitation, non-writablestorage media (e.g., CD-ROM), writable storage media (e.g., a floppydiskette, hard disk drive, read/write CD ROM, optical media), andcommunication media, such as computer and telephone networks includingEthernet. It should be understood, therefore in such signal-bearingmedia when carrying or encoding computer readable instructions thatdirect method functions in the present invention, represent alternativeembodiments of the present invention. Further, it is understood that thepresent invention may be implemented by a system having means in theform of hardware, software, or a combination of software and hardware asdescribed herein or their equivalent.

While the invention has been particularly shown and described withreference to a preferred embodiment, it will be understood by thoseskilled in the art that various changes in form and detail may be madetherein without departing from the spirit and scope of the invention.

1. A data processing system having a hard disk drive having two modes ofoperation, the hard disk drive comprising: means for setting a desiredtemperature range for a hard disk drive that is being tested; means for,upon determining that a temperature inside the hard disk drive is belowthe desired temperature range, changing a mode of operation of the harddisk drive from a first mode of operation to a second mode of operation,wherein the first mode of operation generates less heat than the secondmode of operation; and means for, upon determining that the temperatureinside the hard disk drive is above the desired temperature range,changing the mode of operation of the hard disk drive from the secondmode of operation to the first mode of operation.
 2. The data processingsystem of claim 1, wherein the first and second modes of operation areseek modes, and wherein the first seek mode is slower than the secondseek mode.
 3. The data processing system of claim 1, wherein the firstmode of operation is an IDLE seek mode and the second mode of operationis a rapid seek mode.
 4. A data processing system of claim 1, whereinthe first mode of operation has a slower disk rotation speed than thesecond mode of operation.
 5. The data processing system of claim 1,wherein the first mode of operation has a slower clock speed than asecond mode of operation for a processor within the hard disk drive. 6.A data processing system having hard disk drive capable of maintaining asteady internal temperature during testing operations of the hard diskdrive, the hard disk drive having two modes of operation, the hard diskdrive comprising: means for setting a desired temperature range for ahard disk drive that is being tested; means for, upon determining that atemperature inside the hard disk drive is below the desired temperaturerange, changing a mode of operation of the hard disk drive from a firstmode of operation to a second mode of operation, wherein the first modeof operation generates less heat than the second mode of operation; andmeans for, upon determining that the temperature inside the hard diskdrive is above the desired temperature range, changing the mode ofoperation of the hard disk drive from the second mode of operation tothe first mode of operation.
 7. The data processing system of claim 6,wherein the first and second modes of operation are seek modes, andwherein the first seek mode is slower than the second seek mode.
 8. Thedata processing system of claim 6, wherein the first mode of operationis an IDLE seek mode and the second mode of operation is a rapid seekmode.
 9. A data processing system of claim 6, wherein the first mode ofoperation has a slower disk rotation speed than the second mode ofoperation.
 10. The data processing system of claim 6, wherein the firstmode of operation has a slower clock speed than a second mode ofoperation for a processor within the hard disk drive.
 11. A dataprocessing system having hard disk drive capable of being rapidly warmedbefore testing, the hard disk drive having a first and second mode ofoperation, the hard disk drive comprising: means for setting a desiredtemperature range for a hard disk drive that is to be tested; and meansfor, upon determining that a temperature inside the hard disk drive isbelow the desired temperature range, setting a mode of operation of thehard disk drive to a first mode of operation, wherein the first mode ofoperation generates more heat than a second mode of operation, until thedesired temperature range is reached.
 12. The data processing system ofclaim 11, wherein the first and second modes of operation are seekmodes, and wherein the first seek mode is faster than the second seekmode.
 13. The data processing system of claim 11, wherein the first modeof operation is a rapid seek mode and the second mode of operation is anIDLE seek mode.
 14. The data processing system of claim 11, wherein thefirst mode of operation has a slower disk rotation speed than the secondmode of operation.
 15. The data processing system of claim 11, whereinthe first mode of operation has a slower clock speed than a second modeof operation for a processor within the hard disk drive.